I suppose my main concern for using tooltips alone to solve the problem that my faculty advocates are interested in is that it's an overly general solution. My layperson's understanding of photonotes is that it's an attempt to specify a standard for storing rich metadata about images. The fact that its main current use is drawing boxes with rollovers doesn't necessarily mean that it will always be so. It seems to me that supporting the broader (larval) standard would be important.
Having said that, it's not entirely clear to me that the two are incompatible. Again, my layperson's understanding of photonotes is that it's mainly a format for metadata. The tools for displaying that metadata are just reference implementations. Could the tooltips code be adapted to display the information from the photonotes spec?
